Trench Gate Device EMI Shielding via Nested Polysilicon
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Solution Overview
Problem
Trench gate devices with super junction structures are susceptible to electromagnetic interference, which affects their performance.
Innovation Solution
A trench gate device is designed with a sandwich structure comprising a polysilicon gate, an intermediate dielectric layer, and an auxiliary polysilicon layer, which reduces the impact of electromagnetic interference by fully filling the trench and forming a source region on the substrate with a well region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a trench gate structure is used to achieve faster switching speed and lower switching loss, then switching performance is improved, but susceptibility to electromagnetic interference increases
Solution Approach 1:
The patent implements a nested structure where the polysilicon gate is surrounded by an intermediate dielectric layer, which is in turn surrounded by an auxiliary polysilicon layer. This nested configuration creates multiple shielding layers within the trench gate structure, effectively reducing electromagnetic interference while preserving the fast switching characteristics of the trench gate design.
Solution Approach 2:
The patent employs a composite structure combining different materials with complementary properties: polysilicon for gate functionality, intermediate dielectric layer for insulation and electromagnetic shielding, and auxiliary polysilicon layer for additional shielding and field control. This composite approach addresses both switching performance and electromagnetic interference resistance.
2Productivity
If the device cell size is reduced to increase integration, then device integration is improved, but electromagnetic interference susceptibility increases
Solution Approach 1:
The nested configuration of polysilicon gate, intermediate dielectric layer, and auxiliary polysilicon layer creates an compact electromagnetic shielding structure that can be integrated into small device cells. The nested design maximizes shielding effectiveness within minimal space, enabling high integration while maintaining EMI resistance.
3Object-affected harmful factors
If an intermediate dielectric layer and auxiliary polysilicon layer are added to reduce electromagnetic interference, then electromagnetic interference resistance is improved, but device complexity increases
Solution Approach 1:
The patent segments the trench gate structure into distinct functional layers: the polysilicon gate for control, the intermediate dielectric layer for shielding and insulation, and the auxiliary polysilicon layer for additional shielding. This segmentation allows each layer to be optimized independently while maintaining overall simplicity through systematic integration.
Solution Approach 2:
The auxiliary polysilicon layer serves multiple functions: electromagnetic shielding, field control, and structural completion of the trench fill. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved EMI resistance.
Data Source
AI summary
A method for manufacturing a trench gate device includes: forming a trench in a substrate with a super junction structure; forming a gate dielectric layer in the trench; forming a polysilicon gate by filling a portion of the trench with polysilicon; forming an intermediate dielectric layer in the trench; forming an auxiliary polysilicon layer by filling a gap in the trench with polysilicon; forming a source region of the trench gate device in the substrate; depositing an interlayer dielectric layer, and forming contacts in the interlayer dielectric layer, wherein the polysilicon gate, the auxiliary polysilicon layer, and the source region are led out from the contacts; and connecting the led-out auxiliary polysilicon layer to the led-out source region.